Mosquitos Grow Resistant to Common Insecticide

"Key weapons in the fight against malaria, pyrethroid insecticides, are losing their edge. Over the past decade, billions of dollars have been spent on distributing long-lasting pyrethroid-treated bed nets and on indoor spraying. Focused in Africa, where most malaria deaths occur, these efforts have greatly reduced the disease's toll. But they have also created intense selection pressure for mosquitoes to develop resistance."